“The immune response appears at different times”: experts evaluated the results of RT tests for antibodies to COVID-19

As a result of a study on the presence of antibodies to the coronavirus COVID-19, conducted in 162 employees of the RT channel, IgM antibodies were found in 13 people, and three others had two types of antibodies: IgM and IgG. The remaining participants in the test were not detected antibodies.

Experts commented on the test results and explained that IgM antibodies are produced in the human body in the first stages after infection, while the presence of IgG indicates the formation of immunity to infection. Employees who were present only IgG antibodies, according to the test results were not found. As a result, 16 of the 162 people who passed the tests were sent to self-isolation.

It should be noted that RT was the first company in Russia whose employees passed screening tests for antibodies to COVID-19. It is these tests that are now being passed by residents of the Chinese city of Wuhan, where in December 2019 the first outbreak of a new type of coronavirus occurred.

The tests were conducted by the Human Stem Cell Institute Institute and the SilkWay Rally Association, which, together with the Russian Ministry of Defense, delivered these test systems from China along with protective equipment for military doctors.

Earlier, the company, on behalf of the Minister of Defense Sergey Shoigu, organized several teleconference bridges between Chinese anti-COVID-19 experts and Russian military doctors. 

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As reported in the instructions for the test, made by the Chinese company Innovita, its clinical trials are based on “clear criteria for diagnosing / eliminating the disease,” clinical trials were conducted in five institutions.

The sensitivity of the test reaches 87.3% with a specificity of 100% (the specificity of the test is its ability to reliably determine the absence of this disease in the patient).

As RT editor-in-chief Margarita Simonyan noted, the channel’s management hoped that testing would help identify employees who were already ill and immune to the coronavirus and who could work while at risk were in isolation.

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“The result shocked us. Of the 162 people (who were tested. - RT ) who have been  ill and have immunity, there is NONE. But 16 people get sick right now! And none of them have symptoms. This is ten percent. Again. TEN PERCENT, ”Margarita Simonyan wrote in her Telegram channel.

From the very beginning of the epidemic, the company has taken precautions that are far ahead of the officially established rules. Even before the introduction of the self-isolation regime in the editorial office, all business trips for employees were canceled, the number of shootings was minimized. Everyone who can work from home was transferred to remote work, said Simonyan.

“If there are so many sick and not a single one who has been ill with immunity, does this mean that we are at the foot of a terrible mountain? If there are so many sick and, thank God, not one dead, does this mean that the mortality from the “crown” is much lower than is commonly thought? ” She wrote, asking experts to comment on the figures obtained as a result of the study.

Interpretation Testing

Experts interviewed by RT told how to interpret the data obtained as a result of testing.

Konstantin Severinov, a specialist in molecular biology, professor at the Skolkovo Institute of Science and Technology, professor at Rutgers University, laboratory head at the Institute of Molecular Genetics of the Russian Academy of Sciences and the Institute of Gene Biology of the Russian Academy of Sciences, explained that antibodies do not indicate the presence of a virus in the human body, but show the body's response to infection , current or already ended.

“The first line of defense is the production of antiviral IgM antibodies, and then longer-lasting immunity, based on IgG, arises. People who have tested positive for IgM should most likely have a current infection, and therefore a standard PCR test would show the presence of virus RNA in their biomaterial. Since you do not have such information and since the subjects had no symptoms, it is possible that we were talking about a false-positive signal due to the low specificity of the antibody test. After all, it is still unclear how specific antibody tests are for COVID, ”the expert explained in an interview with RT.

• How RT employees tested for COVID-19 antibodies

A similar point of view was expressed in a commentary by RT molecular biologist, Doctor of Biological Sciences, professor, corresponding member of the Russian Academy of Sciences, head of the laboratory of biotechnology and virology of the faculty of natural sciences of Novosibirsk State University, Sergei Netesov. The expert emphasized that tests conducted by RT staff were previously approved by the World Health Organization.

“In the USA, a dozen antibody test systems have also been developed, they are pre-registered. But the FDA (Quality Supervision Authority. - RT ) warned that tests should be tested on a panel of sera from people who have clearly had and never had this virus. For example, it should be antibodies from blood banks at the beginning of 2019, the serum of people who have been ill with old, well-studied types of coronavirus. In addition, this system should not change the antigen on which it is built. Then it will be clear what conclusions can be made on its basis, ”the expert explained.

At the same time, the widespread PCR test (polymerase chain reaction) also does not give 100% accuracy, experts say. As Arthur Isaev, Director General of the Stem Cell Institute, explained in an interview with RT, the PCR test should show if there is a virus on the human mucosa. Answering the question why sometimes the PCR test gives a false negative result, the expert noted that errors can occur even at the stage of sampling the material.

“Because some tests react and work when there are 1,000 viral particles. Some - when 100 thousand viral particles or 1 million. These are different numbers, different sensitivity. This is the first. The second - you need to correctly and correctly pick up the smear so that there are viral particles, and this process is quite unpleasant. Plus, the RNA of the virus decomposes quickly enough, so the PCR test does not have 100% accuracy, ”he said.

“In addition, the infection may not be detected simply because the virus is no longer on the mucous membrane. Suppose the immune system has partially overcome it and is already struggling with its consequences, ”the expert added.

Commenting on the results of testing among RT employees, Pavel Volchkov, head of the MIPT laboratory of genomic engineering, virologist and immunologist, noted that IgM antibodies have rather weak activity.

“These are low activity, immature bodies. That is why they work in such a pentamer complex. And, unfortunately, the level of false positive IgM response is quite high. It is also necessary to look at exactly which antigen is used. Most likely, we are talking about protein S - the spike protein, which is most abundantly present on the surface of COVID-19. But all the same, the percentage of false-positive results can be in the region of 10-20%. So, it is possible if three of the tested people had false positive results, then most of them still have antibodies, ”the expert noted.

What to do?

According to experts, people who have tested positive for IgM should undergo additional tests.

“Those who have identified antibodies should also take a PCR test. If it gives a negative result, then most likely they can be considered healthy, and the result of testing for antibodies is a test error. That is, they most likely have antibodies not to COVID-19, but to ordinary colds, ”said Konstantin Severinov.

“In addition, those with antibodies should be tested for nucleic acid. The fact is that the nucleic acid test is more sensitive, and there can be options when there is a viral infection, but there is no antibody response yet. After all, the immune response appears at different times — within a week or two, ”the expert added.

A similar point of view is shared by Sergei Netesov. According to the expert, people who have tested positive for antibodies should not relax. There is a risk that the infection, which is still asymptomatic, will go into the active phase soon.

“There is a risk that the disease will develop. There is also a high probability that they are infected and can transmit the virus. Therefore, such people should remain in isolation, and those who interacted with them are at risk. They need to go through the study again in about ten days, ”the expert explained.

The same recommendations were made by Arthur Isaev. According to the expert, people with IgM antibodies were most likely infected some time ago.

“With a high probability they are now sources of infection. Therefore, based on what we know about the contagious nature of the virus, many people from their environment can also be infected, ”said the expert.

Epidemiological findings

Obviously, the statistics obtained as a result of testing the RT edition (10% of supposedly infected or sick) cannot be extrapolated to the entire population. Otherwise, it would be necessary to talk about at least millions of people infected in only one Moscow, said Konstantin Severinov.

“This is not a question, there are no such number of infections,” the expert emphasized.

As Arthur Isaev explained, journalistic work has its own specifics and is associated with a large number of social contacts. Therefore, it is not worth transferring the data received in RT to the situation in the country.

• RIA News
• © Ilya Pitalev

“Most people still have a significantly lower rate of communication than journalists. They are at home and communicate only with loved ones, ”the expert explained.

When asked whether it can be concluded that mortality from coronavirus is lower than is commonly believed, based on the obtained RT data, experts also answered negatively.

“Firstly, your employees are now in the middle of the infection phase. Perhaps the clinical picture in some of them will manifest itself. They now need to carefully monitor their condition. If symptoms of shortness of breath appear, you should immediately call a doctor, ”Isaev explained.

The expert added that mortality is also highly dependent on the age group. Since the majority of tested RT employees are people aged 20 to 40, their risk of complications was a priori lower than the average.

“Risks increase with age. Therefore, it is not yet possible to draw conclusions based on such a small sample, ”the expert emphasized.

Antibodies and re-infection

It is important that at the moment it is not known whether the presence of antibodies is a guarantee of human invulnerability to coronavirus, experts say. According to experts, so far there is simply no reliable information in the world about whether re-infection of COVID-19 is possible.

As explained by Konstantin Severinov, another unknown is the duration of the generated immunity.

• COVID-19
• Reuters
• © NIAID-RML

“It is possible that immunity, if any, ends in a month, in a year. We just do not know this yet. And in order to understand whether a person is a carrier of infection or if he can already come out of self-isolation, it is necessary to determine the presence or absence of his RNA virus, and not antibodies. People with identified IgM may well have an active phase of infection, but to say it for sure, you need to conduct additional tests for the presence of RNA, ”the expert emphasized.

A similar opinion was expressed by Sergei Netesov. The expert recalled that only a few months have passed since the beginning of the pandemic, and all the accumulated scientific experience on this topic is so far limited by this period.

“We know little about this infection. The experience of China says that antibodies can remain in the body for two to three months. And until it is proved that people with IgG antibodies are protected from reinfection. Data on such cases came from Korea, however, they were criticized by experts from other countries, ”the expert added.

At the same time, for people who have IgG antibodies, there is still a low risk of re-contracting coronavirus, says Arthur Isaev. Although scientists cannot give a 100% guarantee of this yet.

“How much this immunity protects against infection is not yet known. Most likely, for them the risks of getting sick are much lower than for the rest. A 100% guarantee cannot be given; research is needed. It is still unknown until the end what type of immunity plays the main role in the fight against COVID-19. We have antibody immunity, or humoral, and there is cellular immunity - it is also able to play a large role in the response to infection. Summing up, we can say that people with antibodies definitely have immunity, because antibodies are part of it. But how much this immunity protects them is not yet known. ”